Field of the Disclosure
The present disclosure relates to a method and system for controlling a switching frequency, and more particularly, to a technique of securing an output and reducing noise by adjusting a switching frequency of an inverter while a vehicle is being driven.
Description of the Related Art
Generally, an inverter is a circuit configured to convert direct current (DC) power transferred from a battery (e.g., a solar battery array or the like) into a usable alternating current (AC) voltage using a switching circuit. Recently, development of high speed switching devices (e.g., an insulated gate bipolar mode transistor (IGBT) or the like) a switching frequency of a voltage type pulse width modulation (PWM) inverter has been increased to provide improved operational characteristics. However, a load of an induction motor, driven by a PWM inverter requires a high switching frequency to obtain a voltage and a current of a sine wave and a voltage and a current are rapidly adjusted every time a switching operation is performed. In other words, since a voltage and a current are significantly changed at every switching operation, a considerable amount of high frequency leakage current is generated.
In particular, a related art grid-connected inverter that reduces a leakage current is configured to use four switching elements in an inverter component. However, in the related art grid-connected inverter, when electric power is transmitted, a current passage is formed through several switching elements to increase loss. In addition, a rapid change in a voltage and a current each time a switching operation is performed in a switching element also increases a leakage current. In particular, a switching element of an inverter mounted within an electric vehicle or a hybrid vehicle is configured to generate switching noise based on a switching frequency, and here, a low switching frequency is advantageous due to loss in a switching operation. However, in an audio frequency range of a driving environment of a user or a driver or in a vehicle in which noise is generated a high switching frequency is advantageous to reduce noise.
The above information disclosed in this section is merely for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.